As known in the art, WDM (wavelength division multiplexing) refers to optical transmission technology where multiple optical signals are transmitted simultaneously on a single optical fiber using different wavelengths of the light (channels). The ever-growing demand for bandwidth is driven by a wide range of services that are now provided over optical networks, such as transmission of e-mail, video, multimedia and voice.
Wavelength Division Multiplexing (WDM) and lately dense WDM (DWDM) have been developed in order to respond to the demand for bandwidth, and became the transmission technology of choice. D/WDM is a physical layer technology that combines and transmits multiple signals simultaneously at different wavelengths on a same fibre. D/WDM is bit-rate and protocol independent. Accordingly, DWDM-based networks can carry different types of traffic at different speeds over an optical fibre, e.g., transmit data in Internet Protocol (IP), Asynchronous Transfer Mode (ATM), and Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH), at a wide range of bit-rates.
The number of backbone providers increased lately, resulting in important decreases in the profit margin of individual providers, while the demand for bandwidth is still healthy. As a result, service provider business has evolved to a point where the quality of the services offered, and also the time it takes to set up new services became a very important factor. Deployment of new services means adding new network resources (equipment and functionality) and downloading the corresponding software to configure, manage and control these resources. Nonetheless, though the D/WDM helped to increase the bandwidth on a fiber link, it did not help to reduce the cost of the network and the service activation time (also called time-to-bandwidth TTB) for various reasons.
Primarily, the current WDM network is provisioned in a point-to-point configuration, where all channels are terminated (optical-electrical-optical or OEO converted) at each node. With this architecture, each new wavelength must be ordered, deployed and engineered separately, involving manual procedures such as retrieval of resource inventory and evaluation as to whether sufficient resources exist. Such manual procedures are time and labour consuming. Also, these manual procedures are generally carried out only a few times a year, and often do not provide enough lead time for ordering new equipment. As a result, the service activation time remains quite large.
If the resource inventory could be automated important saving in service activation time could be obtained. However, this is not provided for in the current point-to-point architecture.
Another reason for the large network costs and large service activation times is that the current management systems cannot provide true agility at the transport layer due again to the current point-to-point configuration. There is a need to provide the network with efficient ways to allow implementation of new services with minimal costs to the network provider, while achieving rapid time to bandwidth (TTB).
‘Network planning’ is defined as the design of the network involving the architectural/technology selection, economic/budgetary comparisons, dimensioning/sizing the network elements, availability analysis, restoration analysis, demand forecasting, etc.
“Network engineering” is required to generate a physical link design and nodal design that will deliver on the specified network performance so that the provisioning application can establish optimal network operation. The output of the engineering stage feeds into the order process with detailed equipment lists and specifications along with configurations so that the installers know exactly where everything needs to be placed.
“Network commissioning” encompasses the operations of installing the equipment, powering-up the network, and testing while the network management system is not yet in place.
“Network provisioning” involves the intelligence required to translate a request for a service into at least one solution through the installed network.
The term ‘network resources’ or ‘resources’ is defined here as the services and equipment available in a network for serving users' requests. Examples of resources are network elements, such as transponders, regenerators, optical amplifiers, switches, OADMs, dispersion compensating equipment, etc.
Resources are also the wavelengths used to carry the user data signals, the number of ports available on a node and their assignment, the number of ports on the client's equipment and their assignment, the fiber connections between the nodes and the routing map, etc.
Transponders are the interfaces between the transport network and the service platform (e.g. a router, electric/optical cross-connect, ATM switch, SONET equipment). A bidirectional transponder generally comprises a long reach (LR) transmitter-receiver pair (Tx-Rx) on the transport network side, and a short reach (SR) Tx-Rx pair on the service platform side. A transponder processes the LR enabled optical signals to SR enabled signals. Since this processing often involves conversion of the channel wavelength and of the protocol, transmission rate, etc, the transponder effects optical-electrical-optical (OEO) conversion.
Regenerators also comprise a Rx-Tx pair for each channel and for each direction of transmission. A regenerator performs OEO conversion for re-timing, re-shaping and regenerating (amplifying) the optical signal to allow transmission over long distances.
There is a limited numbers of network resources available in a network. It is desirable to manage capacity of the optical network by better allocating these limited resources to requests. Also, if a network resource is nearing exhaust, more often new equipment needs to be deployed. Accordingly, it is desirable to monitor utilization of network resources so that they can be better allocated and new equipment can be ordered in time.
The term “request” or ‘demand’ refers to a user request for a circuit that sources at one node and sinks at another node. A request may have a quantity associated with it. An example of a request is: 2 circuits between Ottawa and New-York with a 0:2 path disjoint protection scheme.